Tyre/road noise modelling through equivalent monopoles: source strengths identification based on experimental acoustic transfer functions

At typical driving speeds, the primary source of vehicle exterior noise is the interaction between the tyre and the road. The introduction of tyre noise regulations has led to a growing interest in developing tyre designs that reduce the emitted noise. In this context, this paper presents an experimental approach to modelling tyre/road noise through equivalent monopole sources. The equivalent monopoles are synthesized from tyre rolling noise measurements conducted on a test rig equipped with a road replica in a semi-anechoic chamber. Additionally, acoustic transfer functions are evaluated using an omnidirectional acoustic source that allows an accurate representation of the test environment. The experimental setup and measurement procedure are described. The synthesized monopoles are used to evaluate the noise radiated by the rolling tyre at additional locations to validate the methodology. The approach is tested on four sets of tyres to assess its applicability to different tyre structures, sizes and tread patterns. Finally, the effectiveness of the equivalent source model in evaluating the relative noise levels of different tyre sets is determined by comparison with the experimental measurements.